This invention deals generally with computers and more specifically with the apparatus for cooling a portable computer when it is located within a docking station.
Despite the increased popularity of portable computers such as laptop or notebook computers for the convenience of their portability, there is widespread appreciation that the battery life and heat dissipation of such portables are limiting factors. To accommodate to these limitations, it is typical to use such portable computers in conjunction with a fixed location which is connected to a power line when the computer is at its xe2x80x9chomexe2x80x9d location. This permits higher power operation without draining the portable""s battery and makes cooling devices such as fans available to cool the portable computer. Better cooling of such devices also permits the computer to run at higher speeds which develop more internal heat.
There have been several devices proposed which attempt to interconnect the heat generating components of a portable computer to the heat dissipating devices in a fixed location docking station, but there are significant problems in that effort. Not only must heat conducting elements in both the portable computer and the docking station align, but various other connections for power and information transfer must also be made. Furthermore, the devices available on the portable computer for these several interconnections are limited. Typically heat transfer connections end up with relatively small heat conduction surfaces such as those derived from insertion of a cylindrical or conical pin into a hole, and contact between the surfaces of such connections are not constant and reliable. Furthermore, such insertion type connectors furnish no significant cooling when the portable computer is not mounted in the docking station.
It would be very beneficial to have large surface area thermal connectors on both the portable computer and the docking station, with low thermal resistance devices to transfer heat to and from such connectors, and with some cooling capability of the portable computer""s thermal connector when the portable computer is not in the docking station.
The present invention provides effective cooling of devices within a portable computer both when the portable computer is mounted in a docking station or attached to a power supply or auxiliary battery and when it is not. This is accomplished by using a large surface heat sink near a surface of the portable computer exposed to the external environment which disposes of heat when the portable computer is detached from the docking station, and this same large surface heat sink is used as a thermal connector to the docking station.
Within the portable computer a heat pipe is attached to the heat source, such as a central processing unit, by a thermally conductive connection. This is typically done by using a thermally conductive socket plate which is held tightly against the heat source with spring clips of some sort. A first heat pipe is attached to the thermally conductive socket so that the heat pipe conducts heat away from the heat source to a heat sink. This arrangement is typical of prior art cooling of computer components.
In the present invention, in addition to the aforementioned heat sink, the first heat pipe attached to the socket at the heat source is also attached to a first thermally conductive plate or other large surface structure mounted near a surface of the portable computer, usually the rear surface of the keyboard portion of the portable computer. This first thermally conductive plate has at least one surface that can be exposed to the outside environment by the removal of a covering shield. It is important that the thermally conductive plate is not directly exposed to the environment since its elevated surface temperature creates a personnel safety hazard. Thus, when the portable computer is not mounted in a docking station, the first plate performs as a heat sink through the vented case and shield to dispose of heat from the heat source. The first plate or other surface structure cools by both radiating heat to the environment and by natural convection.
The effectiveness of the first heat pipe, for that matter of any well designed heat pipe, is such that the temperature of the heat source is maintained essentially at the temperature of the first thermally conducting plate. The result is that the very small computer component located within the body of the portable computer and surrounded by other components, many of them also generating heat, actually runs as cool as if it were mounted on the outside of the portable computer case. In fact, because the cooling effect is directly related to the amount of surface area exposed to a cooler environment, and the first thermally conductive plate or other surface structure has a much larger surface area than the typical internal computer component, an internal component cooled by the apparatus of the invention actually runs cooler than it would if it were itself mounted on the outside of the portable computer case.
The task of the portion of the invention located within the docking station is to cool the first thermally conductive plate or other surface structure better than it is cooled by simply exposing it to the temperature of the outside environment, which typically is room temperature. This additional cooling is accomplished by an arrangement which is similar to the heat pipe and the first thermally conductive plate or other large surface structure within the portable computer.
A second thermally conductive plate or surface structure is located on a surface of the docking station, and this second structure matches and contacts the first conductive plate of the portable computer after the shield has been removed. The second matching structure can be on the surface of the docking station since it is not connected to a heat source when it is exposed and does not pose a personnel safety hazard. The second matching structure therefore is placed into intimate thermal contact with the first plate when the portable computer is mounted into the docking station. The plates or other structures, with large conductive surfaces in contact, are excellent for exchanging heat, so the heat from the first plate flows into the second plate. A second heat pipe is attached to the second plate and transfers heat to a heat sink such as an assembly of fins. These fins can be cooled by either natural or forced air convection.
As with the first heat pipe within the portable computer, the second heat pipe within the docking station conducts the heat so effectively that the second plate is maintained at a temperature essentially the same as the air cooled fins. Then, with only a slight temperature difference across the junction of the first plate and the second plate, the first plate and the heat source are maintained at a temperature only very slightly higher than the temperature of the cooling fins. Furthermore since the cooling fins can be forced air cooled by a fan installed in the docking station, the temperature of the heat source can be lowered dramatically from the temperature which would be maintained if the portable computer were separate from the docking station.
The structure of the invention thereby furnishes improved cooling for the portable computer, not only when the portable computer is in the docking station, but also when the portable computer is detached from the docking station.